The invention relates to a method for regulating a generator system and also relates to a generator system, [as respectively described in the preambles to claim 1 and claim 6] in particular a generator system having a gas turbine and an energy reservoir.
Generator systems which employ xe2x80x9cturbogeneratorsxe2x80x9d are known for the generation of electricity. A turbogenerator has a small gas turbine, for example a microturbine, and an electrical generator/motor. In these systems, gas turbine and generator rotor are connected together by means of a simple shaft so that a change to the utilization of the capacity of the gas turbine has a direct effect on the generator output and, therefore, on the electricity generation. Such a turbogenerator is described in EP-A0xe2x80x2901xe2x80x2218. These turbogenerators are particularly suitable for supplying an isolated electricity supply network.
Gas turbines have relatively high inertia so that they can only achieve an output change of 5 kW per second. This, however, is not sufficient to deal with load changes when an isolated electricity supply network is being operated.
An energy reservoir is therefore employed in EP-A0xe2x80x2901xe2x80x2218; this is supplied by the gas turbine in normal operation and, in the case of an increase in load, supplies the network with the difference relative to the gas turbine output. In isolated network operation, furthermore, the gas turbine is started by means of the energy reservoir.
So that it can also cover large changes in load, the energy reservoir must be designed to be relatively large. This makes a substantial contribution to the costs of the installation and to its size. A further disadvantage is that the efficiency of the small output station is relatively poor during load changes because the turbine has a massively increased requirement for fuel.
The object of the invention is, therefore, to create a method of regulating a generator system and to create a generator system, which method and system obviate the disadvantages mentioned above.
This object is achieved by a method with the features of claim 1 and a generator system with the features of claim 6.
In the event of a change in load in a generator system driven by a gas turbine, the invention provides for an energy reservoir to be used not only to supply an energy difference to the network but also to supply energy to the generator. During load changes, therefore, the generator is employed as a motor for accelerating the gas turbine so that the latter can again itself supply the energy required as soon as possible.
This massively reduces the reaction time of the gas turbine. In this system, the energy reservoir has to supply less energy overall to the total system, i.e. to the as network and the generator, than energy reservoirs which only ensure a network-end supply of the energy difference. An energy reservoir with less storage capacity therefore suffices.
The generator system according to the invention has, furthermore, an increased efficiency because the energy for accelerating the turbine does not, or only to a small extent, originate from the fuel and the essential proportion is supplied in the form of electrical energy.
Further advantageous variants of the method and advantageous embodiments are given in the sub-claims.